Auto merge of rust-lang#133905 - jhpratt:rollup-iho8sl1, r=jhpratt

Rollup of 6 pull requests

Successful merges:

 - rust-lang#127565 (Teach rustc about the Xtensa VaListImpl)
 - rust-lang#133844 (clarify simd_relaxed_fma non-determinism)
 - rust-lang#133867 (Fix "std" support status of some tier 3 targets)
 - rust-lang#133882 (Improve comments for the default backtrace printer)
 - rust-lang#133888 (Improve bootstrap job objects)
 - rust-lang#133898 (skip `setup::Hook` on non-git sources)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_codegen_llvm/src/va_arg.rs

@@ -10,15 +10,23 @@ use crate::type_::Type;
 use crate::type_of::LayoutLlvmExt;
 use crate::value::Value;
 
+fn round_up_to_alignment<'ll>(
+    bx: &mut Builder<'_, 'll, '_>,
+    mut value: &'ll Value,
+    align: Align,
+) -> &'ll Value {
+    value = bx.add(value, bx.cx().const_i32(align.bytes() as i32 - 1));
+    return bx.and(value, bx.cx().const_i32(-(align.bytes() as i32)));
+}
+
 fn round_pointer_up_to_alignment<'ll>(
     bx: &mut Builder<'_, 'll, '_>,
     addr: &'ll Value,
     align: Align,
     ptr_ty: &'ll Type,
 ) -> &'ll Value {
     let mut ptr_as_int = bx.ptrtoint(addr, bx.cx().type_isize());
-    ptr_as_int = bx.add(ptr_as_int, bx.cx().const_i32(align.bytes() as i32 - 1));
-    ptr_as_int = bx.and(ptr_as_int, bx.cx().const_i32(-(align.bytes() as i32)));
+    ptr_as_int = round_up_to_alignment(bx, ptr_as_int, align);
     bx.inttoptr(ptr_as_int, ptr_ty)
 }
 
@@ -270,6 +278,106 @@ fn emit_s390x_va_arg<'ll, 'tcx>(
     bx.load(val_type, val_addr, layout.align.abi)
 }
 
+fn emit_xtensa_va_arg<'ll, 'tcx>(
+    bx: &mut Builder<'_, 'll, 'tcx>,
+    list: OperandRef<'tcx, &'ll Value>,
+    target_ty: Ty<'tcx>,
+) -> &'ll Value {
+    // Implementation of va_arg for Xtensa. There doesn't seem to be an authoritative source for
+    // this, other than "what GCC does".
+    //
+    // The va_list type has three fields:
+    // struct __va_list_tag {
+    //   int32_t *va_stk; // Arguments passed on the stack
+    //   int32_t *va_reg; // Arguments passed in registers, saved to memory by the prologue.
+    //   int32_t va_ndx; // Offset into the arguments, in bytes
+    // };
+    //
+    // The first 24 bytes (equivalent to 6 registers) come from va_reg, the rest from va_stk.
+    // Thus if va_ndx is less than 24, the next va_arg *may* read from va_reg,
+    // otherwise it must come from va_stk.
+    //
+    // Primitive arguments are never split between registers and the stack. For example, if loading an 8 byte
+    // primitive value and va_ndx = 20, we instead bump the offset and read everything from va_stk.
+    let va_list_addr = list.immediate();
+    // FIXME: handle multi-field structs that split across regsave/stack?
+    let layout = bx.cx.layout_of(target_ty);
+    let from_stack = bx.append_sibling_block("va_arg.from_stack");
+    let from_regsave = bx.append_sibling_block("va_arg.from_regsave");
+    let end = bx.append_sibling_block("va_arg.end");
+
+    // (*va).va_ndx
+    let va_reg_offset = 4;
+    let va_ndx_offset = va_reg_offset + 4;
+    let offset_ptr =
+        bx.inbounds_gep(bx.type_i8(), va_list_addr, &[bx.cx.const_usize(va_ndx_offset)]);
+
+    let offset = bx.load(bx.type_i32(), offset_ptr, bx.tcx().data_layout.i32_align.abi);
+    let offset = round_up_to_alignment(bx, offset, layout.align.abi);
+
+    let slot_size = layout.size.align_to(Align::from_bytes(4).unwrap()).bytes() as i32;
+
+    // Update the offset in va_list, by adding the slot's size.
+    let offset_next = bx.add(offset, bx.const_i32(slot_size));
+
+    // Figure out where to look for our value. We do that by checking the end of our slot (offset_next).
+    // If that is within the regsave area, then load from there. Otherwise load from the stack area.
+    let regsave_size = bx.const_i32(24);
+    let use_regsave = bx.icmp(IntPredicate::IntULE, offset_next, regsave_size);
+    bx.cond_br(use_regsave, from_regsave, from_stack);
+
+    bx.switch_to_block(from_regsave);
+    // update va_ndx
+    bx.store(offset_next, offset_ptr, bx.tcx().data_layout.pointer_align.abi);
+
+    // (*va).va_reg
+    let regsave_area_ptr =
+        bx.inbounds_gep(bx.type_i8(), va_list_addr, &[bx.cx.const_usize(va_reg_offset)]);
+    let regsave_area =
+        bx.load(bx.type_ptr(), regsave_area_ptr, bx.tcx().data_layout.pointer_align.abi);
+    let regsave_value_ptr = bx.inbounds_gep(bx.type_i8(), regsave_area, &[offset]);
+    bx.br(end);
+
+    bx.switch_to_block(from_stack);
+
+    // The first time we switch from regsave to stack we needs to adjust our offsets a bit.
+    // va_stk is set up such that the first stack argument is always at va_stk + 32.
+    // The corrected offset is written back into the va_list struct.
+
+    // let offset_corrected = cmp::max(offset, 32);
+    let stack_offset_start = bx.const_i32(32);
+    let needs_correction = bx.icmp(IntPredicate::IntULE, offset, stack_offset_start);
+    let offset_corrected = bx.select(needs_correction, stack_offset_start, offset);
+
+    // let offset_next_corrected = offset_corrected + slot_size;
+    // va_ndx = offset_next_corrected;
+    let offset_next_corrected = bx.add(offset_next, bx.const_i32(slot_size));
+    // update va_ndx
+    bx.store(offset_next_corrected, offset_ptr, bx.tcx().data_layout.pointer_align.abi);
+
+    // let stack_value_ptr = unsafe { (*va).va_stk.byte_add(offset_corrected) };
+    let stack_area_ptr = bx.inbounds_gep(bx.type_i8(), va_list_addr, &[bx.cx.const_usize(0)]);
+    let stack_area = bx.load(bx.type_ptr(), stack_area_ptr, bx.tcx().data_layout.pointer_align.abi);
+    let stack_value_ptr = bx.inbounds_gep(bx.type_i8(), stack_area, &[offset_corrected]);
+    bx.br(end);
+
+    bx.switch_to_block(end);
+
+    // On big-endian, for values smaller than the slot size we'd have to align the read to the end
+    // of the slot rather than the start. While the ISA and GCC support big-endian, all the Xtensa
+    // targets supported by rustc are litte-endian so don't worry about it.
+
+    // if from_regsave {
+    //     unsafe { *regsave_value_ptr }
+    // } else {
+    //     unsafe { *stack_value_ptr }
+    // }
+    assert!(bx.tcx().sess.target.endian == Endian::Little);
+    let value_ptr =
+        bx.phi(bx.type_ptr(), &[regsave_value_ptr, stack_value_ptr], &[from_regsave, from_stack]);
+    return bx.load(layout.llvm_type(bx), value_ptr, layout.align.abi);
+}
+
 pub(super) fn emit_va_arg<'ll, 'tcx>(
     bx: &mut Builder<'_, 'll, 'tcx>,
     addr: OperandRef<'tcx, &'ll Value>,
@@ -302,6 +410,7 @@ pub(super) fn emit_va_arg<'ll, 'tcx>(
             let indirect: bool = target_ty_size > 8 || !target_ty_size.is_power_of_two();
             emit_ptr_va_arg(bx, addr, target_ty, indirect, Align::from_bytes(8).unwrap(), false)
         }
+        "xtensa" => emit_xtensa_va_arg(bx, addr, target_ty),
         // For all other architecture/OS combinations fall back to using
         // the LLVM va_arg instruction.
         // https://llvm.org/docs/LangRef.html#va-arg-instruction

compiler/rustc_target/src/spec/targets/armv4t_unknown_linux_gnueabi.rs

@@ -7,7 +7,7 @@ pub(crate) fn target() -> Target {
             description: Some("Armv4T Linux".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: None, // ?
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".into(),

compiler/rustc_target/src/spec/targets/armv5te_unknown_linux_uclibceabi.rs

@@ -7,7 +7,7 @@ pub(crate) fn target() -> Target {
             description: Some("Armv5TE Linux with uClibc".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: None, // ?
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".into(),

compiler/rustc_target/src/spec/targets/m68k_unknown_linux_gnu.rs

@@ -12,7 +12,7 @@ pub(crate) fn target() -> Target {
             description: Some("Motorola 680x0 Linux".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: None, // ?
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "E-m:e-p:32:16:32-i8:8:8-i16:16:16-i32:16:32-n8:16:32-a:0:16-S16".into(),

compiler/rustc_target/src/spec/targets/mips64_openwrt_linux_musl.rs

@@ -17,7 +17,7 @@ pub(crate) fn target() -> Target {
             description: Some("MIPS64 for OpenWrt Linux musl 1.2.3".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: None, // ?
+            std: Some(true),
         },
         pointer_width: 64,
         data_layout: "E-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".into(),

compiler/rustc_target/src/spec/targets/mipsisa32r6_unknown_linux_gnu.rs

@@ -8,7 +8,7 @@ pub(crate) fn target() -> Target {
             description: Some("32-bit MIPS Release 6 Big Endian".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: None, // ?
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".into(),

compiler/rustc_target/src/spec/targets/mipsisa32r6el_unknown_linux_gnu.rs

@@ -7,7 +7,7 @@ pub(crate) fn target() -> Target {
             description: Some("32-bit MIPS Release 6 Little Endian".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: None, // ?
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "e-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64".into(),

compiler/rustc_target/src/spec/targets/mipsisa64r6_unknown_linux_gnuabi64.rs

@@ -8,7 +8,7 @@ pub(crate) fn target() -> Target {
             description: Some("64-bit MIPS Release 6 Big Endian".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: None, // ?
+            std: Some(true),
         },
         pointer_width: 64,
         data_layout: "E-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".into(),

compiler/rustc_target/src/spec/targets/powerpc64_unknown_linux_musl.rs

@@ -14,7 +14,7 @@ pub(crate) fn target() -> Target {
             description: Some("64-bit PowerPC Linux with musl 1.2.3".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: None, // ?
+            std: Some(true),
         },
         pointer_width: 64,
         data_layout: "E-m:e-Fn32-i64:64-n32:64-S128-v256:256:256-v512:512:512".into(),

compiler/rustc_target/src/spec/targets/powerpc64le_unknown_freebsd.rs

@@ -12,8 +12,8 @@ pub(crate) fn target() -> Target {
         metadata: crate::spec::TargetMetadata {
             description: Some("PPC64LE FreeBSD".into()),
             tier: Some(3),
-            host_tools: Some(false),
-            std: Some(false),
+            host_tools: Some(true),
+            std: Some(true),
         },
         pointer_width: 64,
         data_layout: "e-m:e-Fn32-i64:64-n32:64".into(),

compiler/rustc_target/src/spec/targets/powerpc64le_unknown_linux_musl.rs

@@ -13,7 +13,7 @@ pub(crate) fn target() -> Target {
             description: Some("64-bit PowerPC Linux with musl 1.2.3, Little Endian".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: None, // ?
+            std: Some(true),
         },
         pointer_width: 64,
         data_layout: "e-m:e-Fn32-i64:64-n32:64-S128-v256:256:256-v512:512:512".into(),

compiler/rustc_target/src/spec/targets/powerpc_unknown_freebsd.rs

@@ -17,7 +17,7 @@ pub(crate) fn target() -> Target {
             description: Some("PowerPC FreeBSD".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: Some(false),
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "E-m:e-p:32:32-Fn32-i64:64-n32".into(),

compiler/rustc_target/src/spec/targets/powerpc_unknown_linux_musl.rs

@@ -13,7 +13,7 @@ pub(crate) fn target() -> Target {
             description: Some("PowerPC Linux with musl 1.2.3".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: None, // ?
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "E-m:e-p:32:32-Fn32-i64:64-n32".into(),

compiler/rustc_target/src/spec/targets/powerpc_unknown_openbsd.rs

@@ -13,7 +13,7 @@ pub(crate) fn target() -> Target {
             description: None,
             tier: Some(3),
             host_tools: Some(false),
-            std: None, // ?
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "E-m:e-p:32:32-Fn32-i64:64-n32".into(),

compiler/rustc_target/src/spec/targets/riscv32gc_unknown_linux_gnu.rs

@@ -9,7 +9,7 @@ pub(crate) fn target() -> Target {
             description: Some("RISC-V Linux (kernel 5.4, glibc 2.33)".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: Some(false),
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-i64:64-n32-S128".into(),

compiler/rustc_target/src/spec/targets/riscv32gc_unknown_linux_musl.rs

@@ -11,7 +11,7 @@ pub(crate) fn target() -> Target {
             ),
             tier: Some(3),
             host_tools: Some(false),
-            std: Some(false),
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-i64:64-n32-S128".into(),

compiler/rustc_target/src/spec/targets/riscv64_linux_android.rs

@@ -9,7 +9,7 @@ pub(crate) fn target() -> Target {
             description: Some("RISC-V 64-bit Android".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: Some(false),
+            std: Some(true),
         },
         pointer_width: 64,
         data_layout: "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128".into(),

compiler/rustc_target/src/spec/targets/riscv64gc_unknown_freebsd.rs

@@ -7,7 +7,7 @@ pub(crate) fn target() -> Target {
             description: Some("RISC-V FreeBSD".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: Some(false),
+            std: Some(true),
         },
         pointer_width: 64,
         data_layout: "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128".into(),

compiler/rustc_target/src/spec/targets/riscv64gc_unknown_fuchsia.rs

@@ -7,7 +7,7 @@ pub(crate) fn target() -> Target {
             description: Some("RISC-V Fuchsia".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: Some(false),
+            std: Some(true),
         },
         pointer_width: 64,
         data_layout: "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128".into(),

compiler/rustc_target/src/spec/targets/riscv64gc_unknown_linux_musl.rs

@@ -9,7 +9,7 @@ pub(crate) fn target() -> Target {
             description: Some("RISC-V Linux (kernel 4.20, musl 1.2.3)".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: Some(false),
+            std: Some(true),
         },
         pointer_width: 64,
         data_layout: "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128".into(),

compiler/rustc_target/src/spec/targets/s390x_unknown_linux_musl.rs

@@ -19,7 +19,7 @@ pub(crate) fn target() -> Target {
             description: Some("S390x Linux (kernel 3.2, musl 1.2.3)".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: Some(false),
+            std: Some(true),
         },
         pointer_width: 64,
         data_layout: "E-m:e-i1:8:16-i8:8:16-i64:64-f128:64-v128:64-a:8:16-n32:64".into(),

compiler/rustc_target/src/spec/targets/thumbv7neon_unknown_linux_musleabihf.rs

@@ -16,7 +16,7 @@ pub(crate) fn target() -> Target {
             description: Some("Thumb2-mode ARMv7-A Linux with NEON, musl 1.2.3".into()),
             tier: Some(3),
             host_tools: Some(false),
-            std: None, // ?
+            std: Some(true),
         },
         pointer_width: 32,
         data_layout: "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64".into(),

compiler/rustc_target/src/spec/targets/x86_64_unknown_linux_none.rs

@@ -14,7 +14,7 @@ pub(crate) fn target() -> Target {
             description: None,
             tier: None,
             host_tools: None,
-            std: None,
+            std: Some(true),
         },
         pointer_width: 64,
         data_layout:

library/core/Cargo.toml

@@ -43,6 +43,7 @@ check-cfg = [
     'cfg(bootstrap)',
     'cfg(no_fp_fmt_parse)',
     'cfg(stdarch_intel_sde)',
+    'cfg(target_arch, values("xtensa"))',
     # core use #[path] imports to portable-simd `core_simd` crate
     # and to stdarch `core_arch` crate which messes-up with Cargo list
     # of declared features, we therefor expect any feature cfg