[llvm-branch-commits] [llvm] 68799e7 - [GlobalOpt] Don't remove inalloca from varargs functions

[Tom Stellard via llvm-branch-commits]

Author: Arthur Eubanks
Date: 2022-11-15T15:40:40-08:00
New Revision: 68799e789fc5f2a5ff25beffa4dc8828780c08fb

URL: https://github.com/llvm/llvm-project/commit/68799e789fc5f2a5ff25beffa4dc8828780c08fb
DIFF: https://github.com/llvm/llvm-project/commit/68799e789fc5f2a5ff25beffa4dc8828780c08fb.diff

LOG: [GlobalOpt] Don't remove inalloca from varargs functions

Varargs and inalloca have a weird interaction where varargs are actually
passed via the inalloca alloca. Removing inalloca breaks the varargs
because they're still not passed as separate arguments.

Fixes #58718

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D137182

(cherry picked from commit 8c49b01a1ee051ab2c09be4cffc83656ccc0fbe6)

Added: 
    llvm/test/Transforms/GlobalOpt/inalloca-varargs.ll

Modified: 
    llvm/lib/Transforms/IPO/GlobalOpt.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index 6df0409256bbd..6fc7b29c5b78a 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -2003,7 +2003,7 @@ OptimizeFunctions(Module &M,
     // FIXME: We should also hoist alloca affected by this to the entry
     // block if possible.
     if (F.getAttributes().hasAttrSomewhere(Attribute::InAlloca) &&
-        !F.hasAddressTaken() && !hasMustTailCallers(&F)) {
+        !F.hasAddressTaken() && !hasMustTailCallers(&F) && !F.isVarArg()) {
       RemoveAttribute(&F, Attribute::InAlloca);
       Changed = true;
     }

diff  --git a/llvm/test/Transforms/GlobalOpt/inalloca-varargs.ll b/llvm/test/Transforms/GlobalOpt/inalloca-varargs.ll
new file mode 100644
index 0000000000000..188210782edd9
--- /dev/null
+++ b/llvm/test/Transforms/GlobalOpt/inalloca-varargs.ll
@@ -0,0 +1,38 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature
+; RUN: opt -passes=globalopt -S < %s | FileCheck %s
+
+define i32 @main(ptr %a) {
+; CHECK-LABEL: define {{[^@]+}}@main
+; CHECK-SAME: (ptr [[A:%.*]]) local_unnamed_addr {
+; CHECK-NEXT:    [[ARGMEM:%.*]] = alloca inalloca <{ ptr, i32 }>, align 4
+; CHECK-NEXT:    store ptr [[A]], ptr [[ARGMEM]], align 8
+; CHECK-NEXT:    [[G0:%.*]] = getelementptr inbounds <{ ptr, i32 }>, ptr [[ARGMEM]], i32 0, i32 1
+; CHECK-NEXT:    store i32 5, ptr [[G0]], align 4
+; CHECK-NEXT:    [[CALL3:%.*]] = call i32 (ptr, ...) @i(ptr inalloca(ptr) [[ARGMEM]])
+; CHECK-NEXT:    ret i32 [[CALL3]]
+;
+  %argmem = alloca inalloca <{ ptr, i32 }>, align 4
+  store ptr %a, ptr %argmem, align 8
+  %g0 = getelementptr inbounds <{ ptr, i32 }>, ptr %argmem, i32 0, i32 1
+  store i32 5, ptr %g0, align 4
+  %call3 = call i32 (ptr, ...) @i(ptr inalloca(ptr) %argmem)
+  ret i32 %call3
+}
+
+define internal i32 @i(ptr inalloca(ptr) %a, ...) {
+; CHECK-LABEL: define {{[^@]+}}@i
+; CHECK-SAME: (ptr inalloca(ptr) [[A:%.*]], ...) unnamed_addr {
+; CHECK-NEXT:    [[AP:%.*]] = alloca ptr, align 4
+; CHECK-NEXT:    call void @llvm.va_start(ptr [[AP]])
+; CHECK-NEXT:    [[ARGP_CUR:%.*]] = load ptr, ptr [[AP]], align 4
+; CHECK-NEXT:    [[L:%.*]] = load i32, ptr [[ARGP_CUR]], align 4
+; CHECK-NEXT:    ret i32 [[L]]
+;
+  %ap = alloca ptr, align 4
+  call void @llvm.va_start(ptr %ap)
+  %argp.cur = load ptr, ptr %ap, align 4
+  %l = load i32, ptr %argp.cur, align 4
+  ret i32 %l
+}
+
+declare void @llvm.va_start(ptr)