[llvm] [X86] Fix expand-fp on optnone functions (PR #156900)

Frederik Harwath via llvm-commits llvm-commits at lists.llvm.org
Thu Sep 4 07:52:46 PDT 2025


https://github.com/frederik-h created https://github.com/llvm/llvm-project/pull/156900

As observed by @mikaelholmen, PR #130988
"[AMDGPU] Implement IR expansion for frem instruction" introduced a regression on x86. Its changes led to the pass being skipped on functions with the optnone attribute. @bjope also noted that a check concerning the optnone handling is wrong.

This patch fixes both issues which in conjunction fix the regression.

>From 1a778ec3c89a890f821816f168568bcd0f1adb30 Mon Sep 17 00:00:00 2001
From: Frederik Harwath <fharwath at amd.com>
Date: Thu, 4 Sep 2025 10:36:45 -0400
Subject: [PATCH] [X86] Fix expand-fp on optnone functions

As observed by @mikaelholmen, PR #130988
"[AMDGPU] Implement IR expansion for frem instruction" introduced
a regression on x86. Its changes led to the pass being skipped on
functions with the optnone attribute. @bjope also noted that
a check concerning the optnone handling is wrong.

This patch fixes both issues which in conjunction fix the regression.
---
 llvm/lib/CodeGen/ExpandFp.cpp                 |   5 +-
 .../X86/expand-large-fp-optnone.ll            | 252 ++++++++++++++++++
 2 files changed, 253 insertions(+), 4 deletions(-)
 create mode 100644 llvm/test/Transforms/ExpandLargeFpConvert/X86/expand-large-fp-optnone.ll

diff --git a/llvm/lib/CodeGen/ExpandFp.cpp b/llvm/lib/CodeGen/ExpandFp.cpp
index adebd704791ee..1fc2277c71693 100644
--- a/llvm/lib/CodeGen/ExpandFp.cpp
+++ b/llvm/lib/CodeGen/ExpandFp.cpp
@@ -1108,14 +1108,11 @@ class ExpandFpLegacyPass : public FunctionPass {
   ExpandFpLegacyPass() : ExpandFpLegacyPass(CodeGenOptLevel::None) {};
 
   bool runOnFunction(Function &F) override {
-    if (skipFunction(F))
-      return false;
-
     auto *TM = &getAnalysis<TargetPassConfig>().getTM<TargetMachine>();
     auto *TLI = TM->getSubtargetImpl(F)->getTargetLowering();
     AssumptionCache *AC = nullptr;
 
-    if (OptLevel != CodeGenOptLevel::None || F.hasOptNone())
+    if (OptLevel != CodeGenOptLevel::None && !F.hasOptNone())
       AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
     return runImpl(F, *TLI, AC);
   }
diff --git a/llvm/test/Transforms/ExpandLargeFpConvert/X86/expand-large-fp-optnone.ll b/llvm/test/Transforms/ExpandLargeFpConvert/X86/expand-large-fp-optnone.ll
new file mode 100644
index 0000000000000..f6be7a97b7cef
--- /dev/null
+++ b/llvm/test/Transforms/ExpandLargeFpConvert/X86/expand-large-fp-optnone.ll
@@ -0,0 +1,252 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple=x86_64 < %s | FileCheck %s
+
+; expand-fp must also run with optnone
+
+; Function Attrs: noinline optnone
+define double @main(i224 %0) #0 {
+; CHECK-LABEL: main:
+; CHECK:       # %bb.0: # %entryitofp-entry
+; CHECK-NEXT:    pushq %rbp
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    pushq %r15
+; CHECK-NEXT:    .cfi_def_cfa_offset 24
+; CHECK-NEXT:    pushq %r14
+; CHECK-NEXT:    .cfi_def_cfa_offset 32
+; CHECK-NEXT:    pushq %r13
+; CHECK-NEXT:    .cfi_def_cfa_offset 40
+; CHECK-NEXT:    pushq %r12
+; CHECK-NEXT:    .cfi_def_cfa_offset 48
+; CHECK-NEXT:    pushq %rbx
+; CHECK-NEXT:    .cfi_def_cfa_offset 56
+; CHECK-NEXT:    subq $88, %rsp
+; CHECK-NEXT:    .cfi_def_cfa_offset 144
+; CHECK-NEXT:    .cfi_offset %rbx, -56
+; CHECK-NEXT:    .cfi_offset %r12, -48
+; CHECK-NEXT:    .cfi_offset %r13, -40
+; CHECK-NEXT:    .cfi_offset %r14, -32
+; CHECK-NEXT:    .cfi_offset %r15, -24
+; CHECK-NEXT:    .cfi_offset %rbp, -16
+; CHECK-NEXT:    movq %rdi, %rax
+; CHECK-NEXT:    orq %rdx, %rax
+; CHECK-NEXT:    movl %ecx, %r8d
+; CHECK-NEXT:    movq %rsi, %r9
+; CHECK-NEXT:    orq %r8, %r9
+; CHECK-NEXT:    xorps %xmm0, %xmm0
+; CHECK-NEXT:    orq %r9, %rax
+; CHECK-NEXT:    je .LBB0_10
+; CHECK-NEXT:    jmp .LBB0_1
+; CHECK-NEXT:  .LBB0_1: # %itofp-if-end
+; CHECK-NEXT:    movslq %ecx, %rax
+; CHECK-NEXT:    movq %rax, %r9
+; CHECK-NEXT:    sarq $31, %r9
+; CHECK-NEXT:    sarq $63, %rax
+; CHECK-NEXT:    xorq %rax, %rcx
+; CHECK-NEXT:    xorq %rax, %rdx
+; CHECK-NEXT:    xorq %rax, %rsi
+; CHECK-NEXT:    xorq %r9, %rdi
+; CHECK-NEXT:    subq %r9, %rdi
+; CHECK-NEXT:    sbbq %rax, %rsi
+; CHECK-NEXT:    sbbq %rax, %rdx
+; CHECK-NEXT:    sbbq %rax, %rcx
+; CHECK-NEXT:    movq %rcx, %r8
+; CHECK-NEXT:    shldq $32, %rdx, %r8
+; CHECK-NEXT:    bsrq %r8, %rax
+; CHECK-NEXT:    xorl $63, %eax
+; CHECK-NEXT:    movq %rdx, %r10
+; CHECK-NEXT:    shldq $32, %rsi, %r10
+; CHECK-NEXT:    bsrq %r10, %r11
+; CHECK-NEXT:    xorl $63, %r11d
+; CHECK-NEXT:    orl $64, %r11d
+; CHECK-NEXT:    testq %r8, %r8
+; CHECK-NEXT:    cmovnel %eax, %r11d
+; CHECK-NEXT:    movq %rsi, %rbx
+; CHECK-NEXT:    shldq $32, %rdi, %rbx
+; CHECK-NEXT:    bsrq %rbx, %r14
+; CHECK-NEXT:    xorl $63, %r14d
+; CHECK-NEXT:    movq %rdi, %rax
+; CHECK-NEXT:    shlq $32, %rax
+; CHECK-NEXT:    bsrq %rax, %rax
+; CHECK-NEXT:    xorl $63, %eax
+; CHECK-NEXT:    orl $64, %eax
+; CHECK-NEXT:    testq %rbx, %rbx
+; CHECK-NEXT:    cmovnel %r14d, %eax
+; CHECK-NEXT:    subl $-128, %eax
+; CHECK-NEXT:    orq %r8, %r10
+; CHECK-NEXT:    cmovnel %r11d, %eax
+; CHECK-NEXT:    movl $224, %r11d
+; CHECK-NEXT:    subl %eax, %r11d
+; CHECK-NEXT:    movl $223, %r10d
+; CHECK-NEXT:    subl %eax, %r10d
+; CHECK-NEXT:    cmpl $53, %r11d
+; CHECK-NEXT:    jle .LBB0_8
+; CHECK-NEXT:  # %bb.2: # %itofp-if-then4
+; CHECK-NEXT:    movl %r11d, %r8d
+; CHECK-NEXT:    subl $54, %r8d
+; CHECK-NEXT:    je .LBB0_4
+; CHECK-NEXT:    jmp .LBB0_3
+; CHECK-NEXT:  .LBB0_3: # %itofp-if-then4
+; CHECK-NEXT:    movl %r11d, %r8d
+; CHECK-NEXT:    subl $55, %r8d
+; CHECK-NEXT:    jne .LBB0_5
+; CHECK-NEXT:  # %bb.11:
+; CHECK-NEXT:    jmp .LBB0_6
+; CHECK-NEXT:  .LBB0_4: # %itofp-sw-bb
+; CHECK-NEXT:    movq %rsi, %rax
+; CHECK-NEXT:    shldq $1, %rdi, %rax
+; CHECK-NEXT:    movq %rdx, %r8
+; CHECK-NEXT:    shldq $1, %rsi, %r8
+; CHECK-NEXT:    shldq $1, %rdx, %rcx
+; CHECK-NEXT:    addq %rdi, %rdi
+; CHECK-NEXT:    movq %rax, %rsi
+; CHECK-NEXT:    movq %r8, %rdx
+; CHECK-NEXT:    jmp .LBB0_6
+; CHECK-NEXT:  .LBB0_5: # %itofp-sw-default
+; CHECK-NEXT:    movq %rdi, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq %rsi, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq %rdx, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movl %ecx, %r8d
+; CHECK-NEXT:    movq %r8, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movb $-87, %r8b
+; CHECK-NEXT:    subb %al, %r8b
+; CHECK-NEXT:    movb %r8b, %bl
+; CHECK-NEXT:    shrb $6, %bl
+; CHECK-NEXT:    movzbl %bl, %r12d
+; CHECK-NEXT:    movq $0, {{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq $0, (%rsp)
+; CHECK-NEXT:    movq $0, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq $0, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq -24(%rsp,%r12,8), %rbx
+; CHECK-NEXT:    movq -32(%rsp,%r12,8), %r13
+; CHECK-NEXT:    movq %rcx, %rbp
+; CHECK-NEXT:    movb %r8b, %cl
+; CHECK-NEXT:    movq %r13, %r14
+; CHECK-NEXT:    shrdq %cl, %rbx, %r14
+; CHECK-NEXT:    movq %r14, {{[-0-9]+}}(%r{{[sb]}}p) # 8-byte Spill
+; CHECK-NEXT:    movq -48(%rsp,%r12,8), %r15
+; CHECK-NEXT:    movq -40(%rsp,%r12,8), %r12
+; CHECK-NEXT:    movb %r8b, %cl
+; CHECK-NEXT:    movq %r12, %r14
+; CHECK-NEXT:    shrdq %cl, %r13, %r14
+; CHECK-NEXT:    movb %r8b, %cl
+; CHECK-NEXT:    shrq %cl, %rbx
+; CHECK-NEXT:    movb %r8b, %cl
+; CHECK-NEXT:    shrdq %cl, %r12, %r15
+; CHECK-NEXT:    addb $55, %al
+; CHECK-NEXT:    movq %rdi, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq %rsi, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq %rdx, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq %rbp, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq $0, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq $0, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq $0, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq $0, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movb %al, %cl
+; CHECK-NEXT:    shrb $3, %cl
+; CHECK-NEXT:    andb $24, %cl
+; CHECK-NEXT:    negb %cl
+; CHECK-NEXT:    movsbq %cl, %rdx
+; CHECK-NEXT:    movq -80(%rsp,%rdx), %rsi
+; CHECK-NEXT:    movq -72(%rsp,%rdx), %rdi
+; CHECK-NEXT:    movq -64(%rsp,%rdx), %r8
+; CHECK-NEXT:    movb %al, %cl
+; CHECK-NEXT:    movq %r8, %r12
+; CHECK-NEXT:    shldq %cl, %rdi, %r12
+; CHECK-NEXT:    movb %al, %cl
+; CHECK-NEXT:    movq %rsi, %r13
+; CHECK-NEXT:    shlq %cl, %r13
+; CHECK-NEXT:    orq %r12, %r13
+; CHECK-NEXT:    movq -56(%rsp,%rdx), %rdx
+; CHECK-NEXT:    movb %al, %cl
+; CHECK-NEXT:    shldq %cl, %r8, %rdx
+; CHECK-NEXT:    movl %edx, %edx
+; CHECK-NEXT:    movb %al, %cl
+; CHECK-NEXT:    shldq %cl, %rsi, %rdi
+; CHECK-NEXT:    orq %rdx, %rdi
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    orq %rdi, %r13
+; CHECK-NEXT:    setne %al
+; CHECK-NEXT:    orq %rax, %r15
+; CHECK-NEXT:    movq %r15, %rdi
+; CHECK-NEXT:    movq %r14, %rsi
+; CHECK-NEXT:    movq {{[-0-9]+}}(%r{{[sb]}}p), %rdx # 8-byte Reload
+; CHECK-NEXT:    movq %rbx, %rcx
+; CHECK-NEXT:    jmp .LBB0_6
+; CHECK-NEXT:  .LBB0_6: # %itofp-sw-epilog
+; CHECK-NEXT:    movl %edi, %eax
+; CHECK-NEXT:    shrl $2, %eax
+; CHECK-NEXT:    andl $1, %eax
+; CHECK-NEXT:    orq %rax, %rdi
+; CHECK-NEXT:    addq $1, %rdi
+; CHECK-NEXT:    adcq $0, %rsi
+; CHECK-NEXT:    adcq $0, %rdx
+; CHECK-NEXT:    adcq $0, %rcx
+; CHECK-NEXT:    movq %rsi, %rdx
+; CHECK-NEXT:    shldq $62, %rdi, %rdx
+; CHECK-NEXT:    movq %rdx, %rax
+; CHECK-NEXT:    shrq $32, %rax
+; CHECK-NEXT:    btq $55, %rdi
+; CHECK-NEXT:    jae .LBB0_9
+; CHECK-NEXT:    jmp .LBB0_7
+; CHECK-NEXT:  .LBB0_7: # %itofp-if-then20
+; CHECK-NEXT:    shldq $61, %rdi, %rsi
+; CHECK-NEXT:    movq %rsi, %rax
+; CHECK-NEXT:    shrq $32, %rax
+; CHECK-NEXT:    movq %rsi, %rdx
+; CHECK-NEXT:    movl %r11d, %r10d
+; CHECK-NEXT:    jmp .LBB0_9
+; CHECK-NEXT:  .LBB0_8: # %itofp-if-else
+; CHECK-NEXT:    movq %rdi, {{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq %rsi, {{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq %rdx, {{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq %rcx, {{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq $0, {{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq $0, {{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq $0, {{[0-9]+}}(%rsp)
+; CHECK-NEXT:    movq $0, {{[0-9]+}}(%rsp)
+; CHECK-NEXT:    addb $85, %al
+; CHECK-NEXT:    movb %al, %cl
+; CHECK-NEXT:    shrb $3, %cl
+; CHECK-NEXT:    andb $24, %cl
+; CHECK-NEXT:    negb %cl
+; CHECK-NEXT:    movsbq %cl, %rcx
+; CHECK-NEXT:    movq 48(%rsp,%rcx), %rdx
+; CHECK-NEXT:    movb %al, %cl
+; CHECK-NEXT:    shlq %cl, %rdx
+; CHECK-NEXT:    movq %rdx, %rax
+; CHECK-NEXT:    shrq $32, %rax
+; CHECK-NEXT:  .LBB0_9: # %itofp-if-end26
+; CHECK-NEXT:    andl $-2147483648, %r9d # imm = 0x80000000
+; CHECK-NEXT:    shll $20, %r10d
+; CHECK-NEXT:    addl $1072693248, %r10d # imm = 0x3FF00000
+; CHECK-NEXT:    andl $1048575, %eax # imm = 0xFFFFF
+; CHECK-NEXT:    orl %r9d, %eax
+; CHECK-NEXT:    orl %r10d, %eax
+; CHECK-NEXT:    movl %eax, %eax
+; CHECK-NEXT:    shlq $32, %rax
+; CHECK-NEXT:    movabsq $4294967295, %rcx # imm = 0xFFFFFFFF
+; CHECK-NEXT:    andq %rcx, %rdx
+; CHECK-NEXT:    orq %rdx, %rax
+; CHECK-NEXT:    movq %rax, %xmm0
+; CHECK-NEXT:  .LBB0_10: # %itofp-return
+; CHECK-NEXT:    addq $88, %rsp
+; CHECK-NEXT:    .cfi_def_cfa_offset 56
+; CHECK-NEXT:    popq %rbx
+; CHECK-NEXT:    .cfi_def_cfa_offset 48
+; CHECK-NEXT:    popq %r12
+; CHECK-NEXT:    .cfi_def_cfa_offset 40
+; CHECK-NEXT:    popq %r13
+; CHECK-NEXT:    .cfi_def_cfa_offset 32
+; CHECK-NEXT:    popq %r14
+; CHECK-NEXT:    .cfi_def_cfa_offset 24
+; CHECK-NEXT:    popq %r15
+; CHECK-NEXT:    .cfi_def_cfa_offset 16
+; CHECK-NEXT:    popq %rbp
+; CHECK-NEXT:    .cfi_def_cfa_offset 8
+; CHECK-NEXT:    retq
+entry:
+  %x = sitofp i224 %0 to double
+  ret double %x
+}
+
+attributes #0 = { noinline optnone }



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