llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-llvm-regalloc Author: None (llvmbot) <details> <summary>Changes</summary> Backport c80c09f3e380a0a2b00b36bebf72f43271a564c1 Requested by: @<!-- -->DimitryAndric --- Full diff: https://github.com/llvm/llvm-project/pull/102207.diff 3 Files Affected: - (modified) llvm/include/llvm/Support/MathExtras.h (+8) - (modified) llvm/lib/CodeGen/CalcSpillWeights.cpp (+6-5) - (added) llvm/test/CodeGen/X86/pr99396.ll (+56) ``````````diff diff --git a/llvm/include/llvm/Support/MathExtras.h b/llvm/include/llvm/Support/MathExtras.h index 0d0fa826f7bba..e568e42afcf4d 100644 --- a/llvm/include/llvm/Support/MathExtras.h +++ b/llvm/include/llvm/Support/MathExtras.h @@ -770,6 +770,14 @@ std::enable_if_t<std::is_signed_v<T>, T> MulOverflow(T X, T Y, T &Result) { #endif } +/// Type to force float point values onto the stack, so that x86 doesn't add +/// hidden precision, avoiding rounding differences on various platforms. +#if defined(__i386__) || defined(_M_IX86) +using stack_float_t = volatile float; +#else +using stack_float_t = float; +#endif + } // namespace llvm #endif diff --git a/llvm/lib/CodeGen/CalcSpillWeights.cpp b/llvm/lib/CodeGen/CalcSpillWeights.cpp index 1d767a3484bca..9d8c9119f7719 100644 --- a/llvm/lib/CodeGen/CalcSpillWeights.cpp +++ b/llvm/lib/CodeGen/CalcSpillWeights.cpp @@ -22,6 +22,7 @@ #include "llvm/CodeGen/TargetSubtargetInfo.h" #include "llvm/CodeGen/VirtRegMap.h" #include "llvm/Support/Debug.h" +#include "llvm/Support/MathExtras.h" #include "llvm/Support/raw_ostream.h" #include <cassert> #include <tuple> @@ -257,7 +258,9 @@ float VirtRegAuxInfo::weightCalcHelper(LiveInterval &LI, SlotIndex *Start, return -1.0f; } - float Weight = 1.0f; + // Force Weight onto the stack so that x86 doesn't add hidden precision, + // similar to HWeight below. + stack_float_t Weight = 1.0f; if (IsSpillable) { // Get loop info for mi. if (MI->getParent() != MBB) { @@ -284,11 +287,9 @@ float VirtRegAuxInfo::weightCalcHelper(LiveInterval &LI, SlotIndex *Start, Register HintReg = copyHint(MI, LI.reg(), TRI, MRI); if (!HintReg) continue; - // Force hweight onto the stack so that x86 doesn't add hidden precision, + // Force HWeight onto the stack so that x86 doesn't add hidden precision, // making the comparison incorrectly pass (i.e., 1 > 1 == true??). - // - // FIXME: we probably shouldn't use floats at all. - volatile float HWeight = Hint[HintReg] += Weight; + stack_float_t HWeight = Hint[HintReg] += Weight; if (HintReg.isVirtual() || MRI.isAllocatable(HintReg)) CopyHints.insert(CopyHint(HintReg, HWeight)); } diff --git a/llvm/test/CodeGen/X86/pr99396.ll b/llvm/test/CodeGen/X86/pr99396.ll new file mode 100644 index 0000000000000..f534d32038c22 --- /dev/null +++ b/llvm/test/CodeGen/X86/pr99396.ll @@ -0,0 +1,56 @@ +; RUN: llc < %s -mtriple=i386-unknown-freebsd -enable-misched -relocation-model=pic | FileCheck %s + +@c = external local_unnamed_addr global ptr + +declare i32 @fn2() local_unnamed_addr + +declare i32 @fn3() local_unnamed_addr + +define noundef i32 @fn4() #0 { +entry: + %tmp0 = load i32, ptr @fn4, align 4 +; CHECK: movl fn4@GOT(%ebx), %edi +; CHECK-NEXT: movl (%edi), %edx + %tmp1 = load ptr, ptr @c, align 4 +; CHECK: movl c@GOT(%ebx), %eax +; CHECK-NEXT: movl (%eax), %esi +; CHECK-NEXT: testl %esi, %esi + %cmp.g = icmp eq ptr %tmp1, null + br i1 %cmp.g, label %if.then.g, label %if.end3.g + +if.then.g: ; preds = %entry + %tmp2 = load i32, ptr inttoptr (i32 1 to ptr), align 4 + %cmp1.g = icmp slt i32 %tmp2, 0 + br i1 %cmp1.g, label %if.then2.g, label %if.end3.g + +if.then2.g: ; preds = %if.then.g + %.g = load volatile i32, ptr null, align 2147483648 + br label %f.exit + +if.end3.g: ; preds = %if.then.g, %entry + %h.i.g = icmp eq i32 %tmp0, 0 + br i1 %h.i.g, label %f.exit, label %while.body.g + +while.body.g: ; preds = %if.end3.g, %if.end8.g + %buff.addr.019.g = phi ptr [ %incdec.ptr.g, %if.end8.g ], [ @fn4, %if.end3.g ] + %g.addr.018.g = phi i32 [ %dec.g, %if.end8.g ], [ %tmp0, %if.end3.g ] + %call4.g = tail call i32 @fn3(ptr %tmp1, ptr %buff.addr.019.g, i32 %g.addr.018.g) + %cmp5.g = icmp slt i32 %call4.g, 0 + br i1 %cmp5.g, label %if.then6.g, label %if.end8.g + +if.then6.g: ; preds = %while.body.g + %call7.g = tail call i32 @fn2(ptr null) + br label %f.exit + +if.end8.g: ; preds = %while.body.g + %dec.g = add i32 %g.addr.018.g, 1 + %incdec.ptr.g = getelementptr i32, ptr %buff.addr.019.g, i32 1 + store i64 0, ptr %tmp1, align 4 + %h.not.g = icmp eq i32 %dec.g, 0 + br i1 %h.not.g, label %f.exit, label %while.body.g + +f.exit: ; preds = %if.end8.g, %if.then6.g, %if.end3.g, %if.then2.g + ret i32 0 +} + +attributes #0 = { "frame-pointer"="all" "tune-cpu"="generic" } `````````` </details> https://github.com/llvm/llvm-project/pull/102207 _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
