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[CGP] Drop nneg flag when moving zext past instruction #72103

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Merged
merged 1 commit into from
Nov 14, 2023
Merged

[CGP] Drop nneg flag when moving zext past instruction #72103

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38 changes: 12 additions & 26 deletions llvm/lib/CodeGen/CodeGenPrepare.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4568,8 +4568,6 @@ Value *TypePromotionHelper::promoteOperandForOther(
// Step #2.
TPT.replaceAllUsesWith(Ext, ExtOpnd);
// Step #3.
Instruction *ExtForOpnd = Ext;

LLVM_DEBUG(dbgs() << "Propagate Ext to operands\n");
for (int OpIdx = 0, EndOpIdx = ExtOpnd->getNumOperands(); OpIdx != EndOpIdx;
++OpIdx) {
Expand Down Expand Up @@ -4597,33 +4595,21 @@ Value *TypePromotionHelper::promoteOperandForOther(
}

// Otherwise we have to explicitly sign extend the operand.
// Check if Ext was reused to extend an operand.
if (!ExtForOpnd) {
// If yes, create a new one.
LLVM_DEBUG(dbgs() << "More operands to ext\n");
Value *ValForExtOpnd = IsSExt ? TPT.createSExt(Ext, Opnd, Ext->getType())
: TPT.createZExt(Ext, Opnd, Ext->getType());
if (!isa<Instruction>(ValForExtOpnd)) {
TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
continue;
}
ExtForOpnd = cast<Instruction>(ValForExtOpnd);
}
Value *ValForExtOpnd = IsSExt
? TPT.createSExt(ExtOpnd, Opnd, Ext->getType())
: TPT.createZExt(ExtOpnd, Opnd, Ext->getType());
TPT.setOperand(ExtOpnd, OpIdx, ValForExtOpnd);
Instruction *InstForExtOpnd = dyn_cast<Instruction>(ValForExtOpnd);
if (!InstForExtOpnd)
continue;

if (Exts)
Exts->push_back(ExtForOpnd);
TPT.setOperand(ExtForOpnd, 0, Opnd);
Exts->push_back(InstForExtOpnd);

// Move the sign extension before the insertion point.
TPT.moveBefore(ExtForOpnd, ExtOpnd);
TPT.setOperand(ExtOpnd, OpIdx, ExtForOpnd);
CreatedInstsCost += !TLI.isExtFree(ExtForOpnd);
// If more sext are required, new instructions will have to be created.
ExtForOpnd = nullptr;
}
if (ExtForOpnd == Ext) {
LLVM_DEBUG(dbgs() << "Extension is useless now\n");
TPT.eraseInstruction(Ext);
CreatedInstsCost += !TLI.isExtFree(InstForExtOpnd);
}
LLVM_DEBUG(dbgs() << "Extension is useless now\n");
TPT.eraseInstruction(Ext);
return ExtOpnd;
}

Expand Down
4 changes: 2 additions & 2 deletions llvm/test/Transforms/CodeGenPrepare/X86/multi-extension.ll
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Expand Up @@ -10,8 +10,8 @@ declare void @bar(i64)
; %or is reachable by both a sext and zext that are going to be promoted.
; It ensures correct operation on PromotedInsts.

; CHECK: %promoted = trunc i32 %or to i16
; CHECK-NEXT: %c = sext i16 %promoted to i64
; CHECK: %promoted3 = trunc i32 %or to i16
; CHECK-NEXT: %c = sext i16 %promoted3 to i64
define i32 @foo(i16 %kkk) {
entry:
%t4 = load i16, ptr @b, align 2
Expand Down
19 changes: 19 additions & 0 deletions llvm/test/Transforms/CodeGenPrepare/X86/pr72046.ll
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@@ -0,0 +1,19 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 3
; RUN: opt -S -codegenprepare -mtriple=x86_64-unknown-unknown < %s | FileCheck %s

; Make sure the nneg flag is dropped when lshr and zext are interchanged.
define i8 @get(ptr %box, i32 %in) {
; CHECK-LABEL: define i8 @get(
; CHECK-SAME: ptr [[BOX:%.*]], i32 [[IN:%.*]]) {
; CHECK-NEXT: [[PROMOTED:%.*]] = zext i32 [[IN]] to i64
; CHECK-NEXT: [[SHR:%.*]] = lshr i64 [[PROMOTED]], 24
; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds i8, ptr [[BOX]], i64 [[SHR]]
; CHECK-NEXT: [[RES:%.*]] = load i8, ptr [[ARRAYIDX]], align 1
; CHECK-NEXT: ret i8 [[RES]]
;
%shr = lshr i32 %in, 24
%idxprom = zext nneg i32 %shr to i64
%arrayidx = getelementptr inbounds i8, ptr %box, i64 %idxprom
%res = load i8, ptr %arrayidx, align 1
ret i8 %res
}
2 changes: 1 addition & 1 deletion llvm/test/Transforms/CodeGenPrepare/X86/promoted-trunc-loc.ll
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@@ -1,7 +1,7 @@
; RUN: opt < %s -codegenprepare -S -mtriple=x86_64-unknown-unknown | FileCheck %s --match-full-lines

; Make sure the promoted trunc doesn't get a debug location associated.
; CHECK: %promoted = trunc i32 %or to i16
; CHECK: %promoted3 = trunc i32 %or to i16

target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.13.0"
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/Transforms/CodeGenPrepare/X86/promoted-zext-debugloc.ll
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@@ -1,7 +1,7 @@
; RUN: opt < %s -codegenprepare -S -mtriple=x86_64-unknown-unknown | FileCheck %s --match-full-lines

; Make sure the promoted zext doesn't get a debug location associated.
; CHECK: %promoted = zext i8 %t to i64
; CHECK: %promoted1 = zext i8 %t to i64

define void @patatino(ptr %p, ptr %q, i32 %b, ptr %addr) !dbg !6 {
entry:
Expand Down