codegen-opt: fix stack alignment

vtjnash · vtjnash · commit cafcd7cdabf5 · 2017-09-26T16:40:57.000-04:00
previously, stack-alignment of, for example, a 12-byte
allocation would be computed to be 16-bytes during codegen
(because of gc-alignment rounding up),
but 8-bytes here (because of this code rounding down)
diff --git a/src/llvm-alloc-opt.cpp b/src/llvm-alloc-opt.cpp
@@ -715,10 +715,7 @@ bool AllocOpt::runOnFunction(Function &F)
             sz += align;
         }
         else if (sz > 1) {
-            align = JL_SMALL_BYTE_ALIGNMENT;
-            while (sz < align) {
-                align = align / 2;
-            }
+            align = llvm::MinAlign(JL_SMALL_BYTE_ALIGNMENT, llvm::NextPowerOf2(sz));
         }
         // No debug info for prolog instructions
         IRBuilder<> prolog_builder(&entry.front());

Original file line number	Diff line number	Diff line change
`@@ -715,10 +715,7 @@ bool AllocOpt::runOnFunction(Function &F)`
`715`	`715`	`sz += align;`
`716`	`716`	`}`
`717`	`717`	`else if (sz > 1) {`
`718`		`- align = JL_SMALL_BYTE_ALIGNMENT;`
`719`		`- while (sz < align) {`
`720`		`- align = align / 2;`
`721`		`- }`
	`718`	`+ align = llvm::MinAlign(JL_SMALL_BYTE_ALIGNMENT, llvm::NextPowerOf2(sz));`
`722`	`719`	`}`
`723`	`720`	`// No debug info for prolog instructions`
`724`	`721`	`IRBuilder<> prolog_builder(&entry.front());`