[AMDGCN] Use ZExt when handling indices in insertment element (#85718)

When i1 true is used as an index, SExt extends it to i32 -1. This would
cause BitVector to overflow.
The language manual have specified that the index shall be treated as an
unsigned number, this patch fixes that.
(https://llvm.org/docs/LangRef.html#insertelement-instruction)

This patch fixes #85717

---------

Signed-off-by: Peter Rong <PeterRong96@gmail.com>

llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp

@@ -1749,7 +1749,7 @@ static bool isInterestingPHIIncomingValue(const Value *V) {
     // Non constant index/out of bounds index -> folding is unlikely.
     // The latter is more of a sanity check because canonical IR should just
     // have replaced those with poison.
-    if (!Idx || Idx->getSExtValue() >= FVT->getNumElements())
+    if (!Idx || Idx->getZExtValue() >= FVT->getNumElements())
       return false;
 
     const auto *VecSrc = IE->getOperand(0);
@@ -1761,7 +1761,7 @@ static bool isInterestingPHIIncomingValue(const Value *V) {
       return false;
 
     CurVal = VecSrc;
-    EltsCovered.set(Idx->getSExtValue());
+    EltsCovered.set(Idx->getZExtValue());
 
     // All elements covered.
     if (EltsCovered.all())

llvm/test/CodeGen/AMDGPU/amdgpu-codegenprepare-break-large-phis.ll

@@ -1197,3 +1197,54 @@ reallyfinally:
   store <5 x double> %val, ptr %out, align 1
   ret void
 }
+
+define amdgpu_kernel void @pr85718(i1 %Bool, ptr %Ptr, <4 x float> %Vec1, <4 x float> %Vec2) {
+; OPT-LABEL: @pr85718(
+; OPT-NEXT:  BB0:
+; OPT-NEXT:    [[I:%.*]] = insertelement <4 x float> [[VEC1:%.*]], float 4.200000e+01, i1 true
+; OPT-NEXT:    br label [[BB1:%.*]]
+; OPT:       BB1:
+; OPT-NEXT:    [[TMP0:%.*]] = phi float [ [[LARGEPHI_EXTRACTSLICE0:%.*]], [[BB2:%.*]] ], [ [[LARGEPHI_EXTRACTSLICE1:%.*]], [[BB1]] ], [ 0.000000e+00, [[BB0:%.*]] ]
+; OPT-NEXT:    [[TMP1:%.*]] = phi float [ [[LARGEPHI_EXTRACTSLICE3:%.*]], [[BB2]] ], [ [[LARGEPHI_EXTRACTSLICE4:%.*]], [[BB1]] ], [ 0.000000e+00, [[BB0]] ]
+; OPT-NEXT:    [[TMP2:%.*]] = phi float [ [[LARGEPHI_EXTRACTSLICE6:%.*]], [[BB2]] ], [ [[LARGEPHI_EXTRACTSLICE7:%.*]], [[BB1]] ], [ 0.000000e+00, [[BB0]] ]
+; OPT-NEXT:    [[TMP3:%.*]] = phi float [ [[LARGEPHI_EXTRACTSLICE9:%.*]], [[BB2]] ], [ [[LARGEPHI_EXTRACTSLICE10:%.*]], [[BB1]] ], [ 0.000000e+00, [[BB0]] ]
+; OPT-NEXT:    [[LARGEPHI_INSERTSLICE0:%.*]] = insertelement <4 x float> poison, float [[TMP0]], i64 0
+; OPT-NEXT:    [[LARGEPHI_INSERTSLICE1:%.*]] = insertelement <4 x float> [[LARGEPHI_INSERTSLICE0]], float [[TMP1]], i64 1
+; OPT-NEXT:    [[LARGEPHI_INSERTSLICE2:%.*]] = insertelement <4 x float> [[LARGEPHI_INSERTSLICE1]], float [[TMP2]], i64 2
+; OPT-NEXT:    [[LARGEPHI_INSERTSLICE3:%.*]] = insertelement <4 x float> [[LARGEPHI_INSERTSLICE2]], float [[TMP3]], i64 3
+; OPT-NEXT:    store <4 x float> [[LARGEPHI_INSERTSLICE3]], ptr [[PTR:%.*]], align 128
+; OPT-NEXT:    [[LARGEPHI_EXTRACTSLICE1]] = extractelement <4 x float> [[VEC2:%.*]], i64 0
+; OPT-NEXT:    [[LARGEPHI_EXTRACTSLICE4]] = extractelement <4 x float> [[VEC2]], i64 1
+; OPT-NEXT:    [[LARGEPHI_EXTRACTSLICE7]] = extractelement <4 x float> [[VEC2]], i64 2
+; OPT-NEXT:    [[LARGEPHI_EXTRACTSLICE10]] = extractelement <4 x float> [[VEC2]], i64 3
+; OPT-NEXT:    br i1 [[BOOL:%.*]], label [[BB1]], label [[BB2]]
+; OPT:       BB2:
+; OPT-NEXT:    [[LARGEPHI_EXTRACTSLICE0]] = extractelement <4 x float> [[I]], i64 0
+; OPT-NEXT:    [[LARGEPHI_EXTRACTSLICE3]] = extractelement <4 x float> [[I]], i64 1
+; OPT-NEXT:    [[LARGEPHI_EXTRACTSLICE6]] = extractelement <4 x float> [[I]], i64 2
+; OPT-NEXT:    [[LARGEPHI_EXTRACTSLICE9]] = extractelement <4 x float> [[I]], i64 3
+; OPT-NEXT:    br label [[BB1]]
+;
+; NOOPT-LABEL: @pr85718(
+; NOOPT-NEXT:  BB0:
+; NOOPT-NEXT:    [[I:%.*]] = insertelement <4 x float> [[VEC1:%.*]], float 4.200000e+01, i1 true
+; NOOPT-NEXT:    br label [[BB1:%.*]]
+; NOOPT:       BB1:
+; NOOPT-NEXT:    [[PHI:%.*]] = phi <4 x float> [ [[I]], [[BB2:%.*]] ], [ [[VEC2:%.*]], [[BB1]] ], [ zeroinitializer, [[BB0:%.*]] ]
+; NOOPT-NEXT:    store <4 x float> [[PHI]], ptr [[PTR:%.*]], align 128
+; NOOPT-NEXT:    br i1 [[BOOL:%.*]], label [[BB1]], label [[BB2]]
+; NOOPT:       BB2:
+; NOOPT-NEXT:    br label [[BB1]]
+;
+BB0:
+  %I = insertelement <4 x float> %Vec1, float 4.200000e+01, i1 true
+  br label %BB1
+
+BB1:                                              ; preds = %BB0, %BB1, %BB2
+  %PHI = phi <4 x float> [ %I, %BB2 ], [ %Vec2, %BB1 ], [ zeroinitializer, %BB0 ]
+  store <4 x float> %PHI, ptr %Ptr, align 128
+  br i1 %Bool, label %BB1, label %BB2
+
+BB2:                                               ; preds = %BB1
+  br label %BB1
+}